Psychotic Disorders in Epilepsy: Do They Differ from Primary Psychosis?

Any attempt to compare the definitions of symptoms listed for "primary psychoses" with those adopted in studies of psychoses in patients with epilepsy (PWE) will encounter problems of heterogeneity within both conditions. In this manuscript, five psychotic illnesses listed in Diagnostic and Statistical Manual of Mental Disorders-5th Edition (DSM-5), that is, brief psychotic illness, schizophreniform disorder, schizophrenia, delusional disorder, and schizoaffective disorder are compared with postictal (or periictal) and interictal psychotic disorders in PWE. After examining definitions of primary psychoses, definitions of psychoses adopted in the papers dealing with postictal and interictal psychoses are summarized. Further, diagnostic criteria of five types of psychotic disorders in PWE proposed in 2007 by Krishnamoorthy et al. are also discussed, which include postictal psychosis, comorbid schizophrenia, iatrogenic psychosis caused by antiepileptic drugs (AEDs) (AED-induced psychotic disorder: AIPD), and forced normalization. Evidently, a comparison between postictal psychosis and schizophrenia is pointless. Likewise, schizophrenia may not be an appropriate counterpart of forced normalization and AIPD, given their acute or subacute course.Based on these preliminary examinations, three questions are selected to compare primary psychoses and psychoses in PWE: Is postictal psychosis different from a brief psychotic disorder? Does epilepsy facilitate or prevent the development of psychosis or vice versa? Is interictal psychosis of epilepsy different from process schizophrenia? In conclusion, antagonism between psychosis and epileptic seizures in a later stage of active epilepsy seems not to be realized without reorganization of the nervous system promoted during an earlier stage. Both genetic predisposition and the summated effects of epileptic activity must be taken into consideration as part of a trial to explain interictal psychosis. Interictal psychosis is an aggregate of miscellaneous disorders, that is, co-morbid schizophrenia, AED-induced psychotic disorders, forced normalization, and "epileptic" interictal psychosis. Data are lacking to conclude whether differences exist between process schizophrenia and "epileptic" interictal psychosis in terms of negative symptoms, specific personal traits, and the "bizarre-ness" of delusory-hallucinatory contents. These discussions may shed light on the essence of process schizophrenia, thus allowing it stand out and receive increased focus.